Troubleshooting Basics

# Basic troubleshooting (deploy-time and startup) Use this when a deploy fails, the service crashes on start, or health checks time out. Keep fixes minimal and redeploy after each change. ## 1) Classify the failure - **Build failure**: errors in build logs, missing dependencies, build command issues. - **Startup failure**: app exits quickly, crashes, or cannot bind to `$PORT`. - **Runtime/health failure**: service is live but health checks fail or 5xx errors. ## 2) Quick checks by class **Build failure** - Confirm the build command is correct for the runtime. - Ensure required dependencies are present in `package.json`, `requirements.txt`, etc. - Check for missing build-time env vars. **Startup failure** - Confirm the start command and working directory. - Ensure port binding is `0.0.0.0:$PORT`. - Check for missing runtime env vars (secrets, DB URLs). **Runtime/health failure** - Verify the health endpoint path and response. - Confirm the app is actually listening on `$PORT`. - Check database connectivity and migrations. ## 3) Map error signatures to fixes Use [error-patterns.md](error-patterns.md) for a compact catalog of common log messages. ## 4) If still blocked Gather the latest build logs and runtime error logs, then consider the optional `render-debug` skill for deeper diagnostics (metrics, DB checks, expanded patterns).